Refrigeration systems and heating, ventilating, and air conditioning (HVAC) systems can be used to regulate the environment within an enclosed space. These systems use a working fluid, or refrigerant, to move heat as desired. The refrigerant typically is contained within a closed system formed from copper tubes.
In the early days of refrigeration, ammonia, carbon dioxide, and other refrigerants were used, but when Freon (dichloro-diflouro-methane) was discovered as a good refrigerant, it became widely adopted for various reasons. Today, because of environmental concerns, other refrigerants are desirable. New refrigerants are in some instances requiring high-pressure systems (compared to Freon based systems). Manufacturing such systems presents many challenges.